1. Field
Implementations described herein generally relate to semiconductor manufacturing and more particularly to an electrostatic chuck and a method of using the same.
2. Description of the Related Art
As the feature size of the device patterns get smaller, the critical dimension (CD) requirements of these features become a more important criterion for stable and repeatable device performance. Allowable CD variation across a substrate processed within a processing chamber is difficult to achieve due to chamber asymmetries such as chamber and substrate temperature, flow conductance, and RF fields.
In processes utilizing an electrostatic chuck, uniformity of etching across the surface of the substrate is challenging due to the non-homogeneous construction of the chuck below the substrate. For example, some regions of the electrostatic chuck have gas holes, while other regions have lift pin holes that are laterally offset from the gas holes. Still other regions have chucking electrodes, while other regions have heater electrodes that are laterally offset from the chucking electrodes. The non-homogeneous construction of the chuck leads to non-uniformity of the radio frequency (RF) fields which directly affect the etching across the surface of the substrate.
The structure of the electrostatic chuck can vary both laterally and azimuthally, uniformity of the RF field between the chuck and substrate is complicated and very difficult to obtain, resulting in local variability in the RF field across the chuck surface. Plasma based processes can be very sensitive to small local RF coupling variations to the electrostatic chuck. Thus, the local RF coupling variations result in non-uniformity of the processing results along the surface of the substrate.
Thus, there is a need for an improved electrostatic chuck.